Airborne vehicles such as high speed aircraft, for example, have their electrical equipment covered by a radome which provides mechanical protection for the equipment and is configured to complement the aerodynamic streamlining of the vehicle. Typically, the antenna system for transmitting and receiving RF energy is mounted in the radome and is actuated to provide mechanical or electronic scanning and rotating of azimuth and elevation angles relative to the vehicle axis. The radome is preferably made of a dielectric material.
One type of radome includes a slot pattern or array in a conductive material on the radome. The slot pattern is positioned and configured with respect to the antenna to match the antenna and maximize the accuracy and directional effect of the transmitted and received signals. This slot pattern must be clearly defined and precisely positioned to obtain the desired results.
The compound curvature resulting from the aerodynamic and electrical requirements of the radome provides a problem in the establishment of the slot array, particularly with slots of very small size. Conventional approaches either place the slot pattern in a flat surface or form the radome of metal with slots formed in the metal. A metal radome shell is thin and therefore difficult to make and handle. Such radome shells may be reinforced after forming with a thin sheet of dielectric material such as fiberglass cloth laminated with epoxy resin. Prior attempts to locate the slots on an arbitrary preformed curved surface have been unsuccessful.
There are various ways to form radar slots on a flat surface such as masked spraying or laminating, for example. These techniques have not proven satisfactory with a surface having a compound curvature. Even a surface with a single curvature cannot be handled effectively with conventional techniques because it is necessary to provide well defined, complete, sharp patterns to obtain the proper electrical characteristics for the radar signal. This is particularly true with slots which are in the dimension range of millimeters.